r/f1visa

I got an email from SEVP as below:
Student Name:
Type of OPT: post-completion

Your OPT authorization period has ended. The Student and Exchange Visitor Program (SEVP) closed your SEVP Portal account. You can no longer access it.

For more information, go to SEVP Portal Help https://studyinthestates.dhs.gov/sevp-portal-helppages on Study in the States
Do not reply to this email. It was sent from a mailbox that is not monitored. You will get no response.

For help with this process, contact the SEVP Response Center:
* Email at SEVP@ice.dhs.gov or
* Telephone at (703) 603-3400 (Monday through Friday 8:00 AM to 6:00 PM ET, except U.S. holidays)

Sincerely,
The Student and Exchange Visitor Program

I am currently waiting for STEM OPT physical card and my 180 days extension had ended last week. I do have an approval from uscis stating that my STEM opt ead is approved. What does the email mean and should I do ?

I just got my post-completion OPT EAD in hand and have found a job related to my degree. My employer is willing to have me start working, but HR says they cannot add me to their payroll system until I have an SSN. I’m applying for one now.
Has anyone actually started working on OPT before receiving their SSN? Like how they persuaded them or is it even possible? Did you report your actual first day of work in the SEVP Portal, and were those days treated as employment rather than OPT unemployment?
I’m especially interested in firsthand experiences with an employer who could not initially enter the employee into payroll.

I appreciate your help from now on.